A multi-finger hand device having a structure similar to that of a human hand is configured such that a plurality of finger mechanisms are provided extensionally from a hand attached to a tip end of an arm, each having a plurality of interjoint elements sequentially connected via a plurality of finger joints.
In this type of multi-finger hand device, there have been known in the prior art those in which, for each finger mechanism, an actuator for driving the finger joints of the finger mechanism is provided apart from the finger mechanism (for example, in the hand or arm), this actuator is connected to the finger mechanism via a wire element and a pulley element onto which the wire element is wound, and the wire element is pulled by the actuator to allow the finger mechanism to perform bending and stretching operations (for example, refer to Japanese Patent Application Laid-Open No.207795 (1985), Japanese Patent Application Laid-Open No. 8178 (1994) or the like).
However, these conventional multi-finger hand devices, being provided with an actuator for each finger mechanism, can control the bending and stretching operations of the respective finger mechanisms independently, while large space is necessary for mounting a number of actuators. Furthermore, since the wire element connecting the finger mechanism and the actuator corresponding to the same are required for each finger mechanism, space for arranging a number of wire elements is also necessary and the arrangement of the wire elements becomes complicated.
In order to solve such inconveniences, it can be considered that, for example, the respective finger mechanisms are biased via springs or the like toward their stretching side or bending side, that the wire elements provided extensionally from the respective finger mechanisms are combined with each other, and that the combined wire elements are pulled by a single actuator, whereby bending operations or stretching operations of the respective finger mechanisms can be performed collectively.
However, in such a case, for example, when the bending operations of the respective finger mechanisms are performed to hold an object, and one of the finger mechanisms touches the object or another obstacle, thereby being disabled to perform the bending operation further, the other finger mechanisms may also be disabled to perform their bending operations further, thereby being disabled to hold the object properly. Furthermore, in a case where the respective finger mechanisms are stretched from the bending state, when one of the finger mechanisms touches an obstacle or the like, thereby being disabled to perform the stretching operation further, the other finger mechanisms are also disabled to perform the stretching operations.
The present invention is achieved in view of the above-mentioned background, and it is an object of the present invention to provide a multi-finger hand device which bends and stretches a plurality of finger mechanisms via wire elements, wherein smooth bending and stretching operations of the finger mechanisms can be performed in holding work of an object or the like while reducing the number of actuators as driving sources of the bending and stretching operations of the finger mechanisms.